HP-UX Workload Manager A.02.03.01 Release Notes for HP-UX 11i V1.0 and HP-UX 11i V2.0

HP-UX Workload Manager Release Notes
Known problems and workarounds
8
Known problems and workarounds
This section discusses problems and workarounds.
High CPU load may reduce CPU allocations of workload groups with
few processes
Issue
The CPU scheduler that WLM uses schedules processes by:
• Distributing all the processes from each workload group in round-robin
fashion starting from the same CPU every time
• Once all the processes are distributed, CPUs with spare cycles inherit
processes from CPUs that are completely busy
Because the round-robin distribution always starts with the same CPU, that
CPU—and other CPUs at the start of the distribution—can quickly become
loaded with processes. For example, assume there are many groups with
just one or two processes. Also assume a single workload group has enough
processes to distribute at least one process per CPU and that each of those
processes consumes all of its CPU’s cycles.
As a result, there are no CPUs with spare cycles to inherit processes. With
all those processes crowded on the first CPUs in the round-robin
distribution, the processes’ associated workload groups may not be able to
get their CPU allocations.
Workaround
On HP-UX 11i V1.0 (B.11.11), install patches PHKL_30032, PHKL_30033,
PHKL_30034, PHKL_30035, PHKL_30036, and PHKL_30037. Install all
these patches at the same time. For patch descriptions, see Table 1-3 on
page 23. These patches address CR# JAGae14311.
On HP-UX 11i V2.0 (B.11.23), install the BUNDLE11i patch bundle. Any
version of this bundle is acceptable.